Generally well known among drivers of motor vehicles is the fact that in the operation of such a vehicle, situations can arise in which the vehicle becomes immobilized due to blockages on the traveled road. For instance, one can think of driving into an impassable place in deep snow, loose sand or into a short and deep depression in the roadway.
As a rule, accomplished drivers with manually operated transmissions of conventional vehicles can free themselves from the mired position by the so-called “back-and-forth” rocking process.
When this occurs, in the case of a vehicle which is motionless although the motor is running, first a clutch pedal is activated, a transmission shift position engaged and then the clutch pedal is released. The vehicle then moves itself until those forces working against it in the direction of travel become so large that the driver must, once again, activate the clutch pedal to avoid stalling the motor. Subsequently, the vehicle rolls back, now beyond its original starting position, until it is stopped in the opposite direction, again by the road obstruction and is, once again, in a standstill condition. At this moment, the driver releases the clutch pedal, now in a chosen gear position, so that the vehicle in its next starting trial tries to overcome the obstructing means by a somewhat longer approach at a higher speed. The resulting rocking process is then repeated until the vehicle frees itself or this method has to be abandoned.
The above method of operation can be supported by well versed drivers, in that this alternating “to-and-fro” synchronistic movement of the vehicle requires the engagement of a forward and a reverse gear stage.
Where vehicles that are equipped with an automatic transmission are concerned, especially in a case of a step-to-step transmission having an automatic starting clutch, the overcoming of such roadway obstructions shows itself as being somewhat more difficult since the driver has no direct influence over the activation of the starting and shifting of the clutch action.
To this end, DE 101 28 853 A1 has let it be known that a motor vehicle with an automatic, double-clutch transmission exists wherein, by way of a particular apparatus, the vehicle can be brought into the above described to-and-fro rocking phase and can be manually operated within this phase.
Furthermore, in this state of the technology, provision is made that in a case of double-clutch transmissions for the carrying out of the rocking process, both a forward gear as well as the reverse gear of the transmission must be capable of engagement. The two clutches of this generally heavy duty transmission can be accordingly so in-and-out engaged alternately, that the vehicle in a roadway blockage, on a short term basis, can be driven forward and then backwards as far as possible. For this operation, an activation apparatus is made available within reach of the driver in which the driver can manually take over the clutch activation and can also be in control of the forward and backward motion of the vehicle as far as any limitation of this arrangement permits.
This activation apparatus can be a component of a shifting device employed for the signaling of ratio changing and/or as a reaction to a desire for a gear stage change, which allows shifting into a rocking process by way of a prior activation of a separate shifting device. Advantageously, it is possible, however, that a shifting device can be installed, where the transmission gear stages can be shifted sequentially up or down.
Even if the known device can be employed with complete advantage for automatic, double-clutch transmissions, nevertheless, this arrangement carries the disadvantage that the rocking process does not run itself automatically, but must be manually and cleverly carried out by the vehicle driver. This places a problem for inexperienced drivers in that they do, indeed, have a device for rocking, but which they are unable to manipulate at its optimum efficiency.
Moreover, this rocking process cannot be used with automatic transmissions, which are based on conventional gearshift.
Giving consideration to this background, the invention should exhibit the possibility that a vehicle with an automatic shift transmission can overcome the described roadway obstructing occurrences. In carrying this possibility out, complete avoidance is to be made, counter to the state of the technology, which calls for a manual intervention of the rocking process to enable inexperienced driver to make the most of their available opportunities. Nevertheless, it is possible that, in addition, a manual means of operation should be made available.